N° 8–2009: ESA to launch two large observatories to look deep into space and time

7 May 2009

Two of the most sophisticated astronomical spacecraft ever built –Herschel and Planck– will be launched by ESA this month towards deep space orbits around a special observation point beyond the Moon's orbit. From there, both spacecraft will begin a revolutionary observation campaign that will further our understanding of the history of the universe.

Herschel is a large far-infrared space telescope designed to study some of the coldest objects in space, in a part of the electromagnetic spectrum still mostly unexplored. Planck is a telescope that will map the fossil light of the universe - light from the Big Bang – with unprecedented sensitivity and accuracy. The two missions are among the most ambitious ever carried out by Europe and mark the crossing of new frontiers in the field of space-based astronomy.

The pair will be lofted in tandem by an Ariane 5 ECA launcher. Lift-off is now scheduled for 15:12 CEST (13:12 GMT) on Thursday 14 May, from Europe's Spaceport in French Guiana. Herschel and Planck will separate shortly after launch and head independently towards the L2 Lagrangian point of the Sun-Earth system, a gravitational stability point suspended in space some 1.5 million kilometres from Earth in the opposite direction to the Sun. While orbiting around that point, they will be able to conduct continuous observations in a thermally-stable environment, far from radiation disturbance caused by the Sun, Earth and Moon.

The 7.5-m-tall, 4-m-wide Herschel is the largest infrared telescope ever launched. The extremely smooth surface of its 3.5-m-diameter primary mirror –made of lightweight silicon carbide– is almost one and a half times bigger than that of Hubble's, and six times bigger than that of its predecessor ISO launched by ESA in 1995.

With its huge light-collection capability and set of sophisticated detectors cooled to the vicinity of absolute zero by over 2000 litres of superfluid helium, Herschel will look at the faintest and farthest infrared sources and peer into the as-yet uncharted far infrared and submillimetric parts of the spectrum.

Herschel will be able to see through the opacity of cosmic dust and gas and observe structures and events far away that date back to the early universe –such as the birth and evolution of early stars and galaxies– ten thousand million years ago, in an effort to determine exactly how it all started. Closer by, within our galaxy, Herschel will also observe extremely cold objects, such as the clouds of dust and interstellar gases from which stars and planets are formed, and even the atmosphere around comets, planets and their moons in our own solar system.

Featuring a 1.5 m telescope and instruments sensitive to microwave radiation, Planck will measure temperature variations in the very early universe. It will monitor the so- called Cosmic Microwave Background, the relic of the very first light ever emitted in space about 380 thousand years after the Big Bang, when the density and temperature of the young universe had decreased enough to finally allow light to separate from matter and travel freely in space.

With its 'heart' operating at unprecedented low temperatures, Planck will deliver unrivalled sensitivity and resolution. By measuring the tiny fluctuations in the temperature of the microwave background radiation, scientists will extract at least 15 times more information about the universe's origin, evolution and future than with its most recent predecessor.

Herschel's detectors will be cooled down to 0.3 degrees above absolute zero. Planck's detectors will reach even colder temperatures, just 0.1 degrees above 0 K. Indeed, throughout the mission, the coldest points of the universe may well be inside its payload. The satellite is planned to take some 500 thousand million of raw samples to produce a set of multi-million-pixel sky maps that will also help scientists to understand the universe's structure and account as never before for all of its constituents. Planck will be able to determine the total amount of atoms in the universe, infer the total density of dark matter –an elusive component still inaccessible to direct observations but ‘visible' through its effects on the surroundings– and even shed new light on the nature of the mysterious dark energy.

Herschel and Planck, two impressive missions designed to revolutionise our understanding of the cosmos, also represent a tremendous technological challenge that has been overcome by ESA thanks to the mobilising of over 100 industrial partners and institutes in Europe, the United States and elsewhere.

Attending the launch

The main launch event for Herschel/Planck will be held at ESOC, the Agency's establishment in Darmstadt, Germany. There, ESA senior management and programme specialists will be on hand to give explanations and interviews.

The Press Centre at ESOC will be open from 10:00 to 18:00 hours, hosting a media workshop from 11:00 to 12:15 hours and the launch event from 14:00 to 16:15 hours.

A live TV transmission of the launch will supply images from Kourou and from mission control at ESOC/Darmstadt to broadcasters (further details will soon be available at http://television.esa.int).

The general public can also follow the launch video transmission via web-streaming at: http://www.esa.int

Media representatives wishing to follow the event at ESOC or watch the launch live from another ESA establishment are requested to fill in the attached accreditation form and fax it back to the venue of their choice.

Note for editors

Herschel and Planck under ESA's Science Programme

Herschel and Planck are the last missions to be launched under ESA's Horizon 2000 long-term plan for space science initiated in 1985, which has already brought the worldwide scientific community a series of trail-blazing successes including: the Integral gamma-ray and XMM-Newton X-ray observatories; the Huygens probe that landed on Saturn's largest moon, Titan; the Ulysses, Soho and Cluster missions monitoring the Sun, its sphere of influence and Sun-Earth interaction; the Smart-1, Mars Express and Venus Express lunar and planetary explorers; and the Rosetta comet chaser currently mid-way to its final target, the nucleus of comet Churyumov-Gerasimenko. Over the past 25 years, the Horizon 2000 plan and its successors Horizon 2000+ and Cosmic Vision, have set the standard for successful space science in Europe and laid the foundations for the future scientific exploration of space, giving Europe international stature when it comes to cooperation.

Herschel and Planck – the result of a huge international effort

Herschel and Planck have been built under a common engineering programme carried out on ESA's behalf by Thales Alenia Space (Cannes, France) as prime contractor, also responsible for the Planck payload module, heading a consortium of industrial partners with Astrium (Friedrichshafen, Germany) responsible for the Herschel payload module and Thales Alenia Space (Turin, Italy) responsible for the service modules. Astrium (Toulouse, France) provided the Herschel telescope. The Planck telescope was provided through collaboration between ESA and the Danish National Space Centre.

Academic and industrial consortia from across the world have designed and manufactured the Herschel and Planck onboard instruments.

Herschel features three instruments: the HIFI high-resolution spectrometer, consortium led by the SRON Netherlands Institute for Space Research (The Netherlands); the PACS camera and imaging spectrometer, consortium led by the Max Planck Institute for Extraterrestrial Physics (Germany); and the SPIRE camera and imaging spectrometer, consortium led by Cardiff University (Wales, United Kingdom). Important contributions were also made by the United States (NASA), Canada and Poland.

Planck features two instruments: the HFI high-frequency instrument, consortium led by the Institut d'Astrophysique Spatiale (France); and the LFI low-frequency instrument, consortium led by the Istituto di Astrofisica Spaziale e Fisica Cosmica (Italy), with the United States (NASA) making an important contribution.